Kill Switch

A kill switch, also known as an e-stop, is a security mechanism used to shut off a device in an emergency situation in which it cannot be shut down in the usual manner. Unlike a normal shut-down switch/procedure, which shuts down all systems in an orderly fashion and turns the machine off without damaging it, a kill switch is designed and configured to a) completely abort the operation at all costs and b) be operable in a manner that is quick, simple (so that even a panicking user with impaired executive function can operate it), and, usually, c) be obvious even to an untrained operator or a bystander. Many kill switches feature a removable barrier or other protection against accidental activation (e.g., a plastic cover that must be lifted or glass that must be broken).

Kill switches are featured especially often as part of mechanisms whose normal operation or foreseeable misuse may cause injury or death; designers who include such switches consider damage to or destruction of the mechanism to be an acceptable cost of preventing that injury or death.